The Adolescent Medicine HIV/AIDS Research Network is a national cooperative project among scientists and clinical centers involved in the care and treatment of adolescents with HIV/AIDS. As a cooperative research project, the Adolescent Medicine HIV/AIDS Research Network will plan and conduct research on the medical, bio-behavioral and psychosocial aspects of HIV/AIDS in adolescents between the ages of 13 and 19 years who are infected with HIV or at high risk for HIV infection. The ultimate goal of the Adolescent Network is to achieve a better understanding of HIV disease progression and its behavioral manifestations in adolescents. Specific aim include: To develop a standardized base protocol to characterize population-based spectrum of disease, disease progression and the effect of co-morbidity with other sexually transmitted diseases and pregnancy in the adolescent population; To recruit 200 HIV-infected adolescents into a standardized base protocol; To develop and implement special studies in the assembled cohort related to the susceptibility, infectivity and transmissibility of HIV in adolescents; To develop and disseminate treatment and policy guidelines specific to HIV-infected adolescents. At the proposed research site, Children's Diagnostic and Treatment Center, a cohort of 30 adolescents between the ages of 12 and 19 will be recruited throughout Broward County; 20 HIV-infected adolescents and 10 non-infected adolescents with high risk behaviors. Clinical, laboratory and psychosocial data will collected at three month intervals for infected adolescents and six month intervals for non- infected adolescents, according to a standardized base protocol. Site- specific special studies may include neurologic and neuro-psychologic studies.